Mercury-arc device



DEIS, 1928.

' V. K. ZWORYKIN MERCURY ARC DEVICE Filed Nov. 21, 1925 Fig. 1.

INVENTOR V/ad/mir/(Zm m AT'TORNEY Patented Dec. 18, 192s.

- UNITED STATES PATENT OFFICE.

VLADIMIR K. ZWOBYKIN, OF SWISSVALE, PENNSYLVANIA, ASSIGNOR TO WES'JQING- HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VAN IA.

MERCURY-ARC DEVICE.

Application filed November 21, 1925. Serial No. 70,558.

My invention relates to mercury-arc discharge devices and it has particular relation to means-for initiating an are upon the surface of the mercury cathode used in such de vices.

Of the many starting devices proposed for mercury-arc tubes, those that have found most general application have involved amovable mechanism for making contact between an auxiliary electrode and the main body of the mercury cathode and starting the are by interrupting the cont-act.

The principal object of my present invention is to provide a starting device which has all the advantages of the devices utilizing mechanical motion of the electrodes, but which obtains astarting are upon the surface of the mercury cathode without mechanical motion ofeither the rectifier or the electrodes.

Another object of my invention is to provide aself-restoring fuse-like mercury thread in the interior of the rectifier and to initiate the rectifier discharge by sending through the mercury thread a current sufficient to interrupt the continuity of the thread and start an arc thereon,thc are being transferred to the main surface of the mercury cathode.

A further object of my invention is the provision of means for utilizing the variation of the conditions in a column of conducting liquid to actuate an operating mechanism in response to a flow of current througl 35. said column. v

According to my'invention, I provide near the surface of the mercury electrode, an insulating body having a perforation com-.

.municating at one end with the body of the mercury cathode and being filled with a thread of mercury. A leading-in 'wirclprovides an electrical connection to the othcr end of'the mercury thread in the perforation. By momentarily sending arelatively large current through the fuse-like mercury thread, the conducting connection effected by the mercury 'thread is blown up and an arc is started which is shitablytransferred to the main surface of the mercury electrode.

The foregoing and other objects of my ,ing

cathode, together with a starting device embodying my invent-ion,

Fig. 3 is a view similar to Fig. 2 embodying 1nodifications of my invention,

Fig. 4 is a sectional view along the line V-'V of Fig. 3, showing the laterally projecting arm near the mercury cathode, and

Fig. 5 is a. view similar to Fig. 2 illustrata still further modification of my invention.

Referring to Fig. 1, I have shown a familiar type oftwo-phase rectifier comprising a 1 glass envelope 1 provided with two anodes 3 and 4 and having a mercury cathode 5 in a depending'portion 6 of the envelope. The rectifier is supplied through a transformer. 7 having a secondary winding 8 having its end terminals connected across the anodes 3 and 4, the midpoint of the secondary winding constitutin one terminal 9 of the direct-current load inot-shown). The mercury cat-hode onstitutesthe other terminal of the dir -cur'rent.load. i

If the discharge tube is out of operation and a load is connected to the rectifier, rectilfication will not start unless electron emission is somehow started upon the surface of the mercury cathode.

My invention contemplates a novel means for initiating an electr n discharge upon the cathode surface by pro%ucing thereon an are without the employment of mechanical current interrupting means in the interior of the reotifier. To this end, I provide a horizontal ing material, such as uartz, disposed adja;

.cent to the surface of t emercury cathode 5 tubular member 12 of heat-resistant insulat 15 into which is sealed a leading-in wire 16 projecting through the walls of the rectifier opening.

To start the rectifier, a current 1s sent through the mercury thread filllng the longitudinal perforation 13 from any convenient source of directcurrent, such, for example, as aflstandard rectifier circuit 20 energ zed by a transformer 21. A switch22 is provlded by means of which the-current supplied by the rectifier 20 to the lea-din -in wire maybe turned on or off at will. Since the currentcarrying capacity of the thread is very small, it is rapidly heated and blown up l1ke a fuse, starting an are which is expelled through the lateral opening '18 to the surface 19 of the arrangement.

mercury cathode. For the purposes of my invention, it is'not material whether the arc develops in the interior of the perforation 13 before the mercury disposed therein 15 expelled through the opening 18o r afterwards, the principal -requirement being that the arc shall be given a good opportumty to transfer to the main surface of the mercury cathode.

The tubular member 12 is provided wlth a bend at its open endin order to increase the resistance to the motion of the mercury through the end opening 14: when a current is sent therethrough and to direct the PI'lIlcipal force and movement of the mercury toward the lateral opening 18 projecting above the "surface of the mercury, as I found that the starting operation is facilitated by such In the preferred construction of my invention, as shown in Fig. 2, the lea-dingin wire 16 projecting into the. pocket 15 of the tubular member 12 is tightly sealed into the from the perforation 13.

quartz body of the member in order to i crease the force tending to expel the inercu y Howeveiggl have obtained very good results with a leading-in wire 16 which is only loosely disposed in the surrounding portion of "the tubular member 12, permitting communication" between the interior of the pocket 15 and thespace above the mercury surface. I

In the modification of my invention shown in Figs. 3 and 4, the depending portion 6 of the discharge tube is provided with a laterally-projectmg extension having a thin her to provide groove or channel 43 in its bottom, which is disposed approximately on the level of the surface of the mercury cathode. The extreme end of the extension 42 is depressed to provide a mercury-filled pocket 45which is provided with a leading-in terminal wire 46. The discharge in the tube is initiated by sending a current through the thread of mercury filling the channel 43 of the extension 42 until the thread-like body is interrupted and an arc is formed thereon.

In the modification of my invention shown in Fig. 5, the depending portion 6 of the. mercury tube is provided with an inwardly" projecting trough having at its bottom a groglil'e or channel 52 which is substantially on t cathode. 'The groove or channel 52 is filled with a thread of mercuryextending between the main body of the mercury cathode 53 and an insulated pocket 54 at the end of the trough near the wall of the vessel, a leading-in wire 55 serving to make electrical connection with the mercury-filled pocket 54. The device in Fig. 5 operates similar to that of Fig. 3.

I claimas my invention: I 1. The combinationwith a mercury-arcdise level of the mercury of the rectifier charge device comprising a vessel and a mercury electrode in said vessel, of a starting means for initiating electron emission upon' the surface of the mercury, comprising a member of insulating materlal having a tubular perforation submerged in the mercury, said' perforation being in communication with the body of mercury and so disposed that it is filled with a threadof mercury, an insulated lead-in connection for said mema current paththrough said thread, said member having a portion opening above the surface of the mercury and communicating with said thread, whereby uponsending current through "said thread, mercury. is expelled through said opening and an arc is started on the mercury surface.

2. The combination. with a mercury-arc discharge device comprising a vessel-and a mercury electrode in said vessel, of a starting means for-initiating electron emission upon the surface of the mercury, comprising an insulating member of heat resistant insulating material partially submerged under the mercury surface, said member having a longitudinal tubular perforation having an open end communicating with the body of mercury, said perforation being closed at .the opposite endand so disposed as to be normally filled with a thread-like column of mercury, an insulatedlead-in connection for said column disposed near the'closed end wherebv a current path is provided through said column, said: member having a lateral perforation extending from said column and opening above the surface of the mercury and adjacent to the same, said member being so arranged that upon sending current through said column, mercury is expelled through said lateral opening and an arc is initiated therethrough.

3. An electrical discharge device comprising a pair of mercury electrodes electrically connected through a narrow channel containing mercury,-substantially parallel to the mercury surfaces and having insulating side in said channel causes its expulsion in. an'

upward direction.

In testimony whereof, I have hereuntosubscribed my name this 13th day of November, 1925.

VLADIMIR K. ZWORY KIN. 

